Tire retreading device



Dec. 14, 1948.

H. V. JAMES TIRE RETREADING DEVICE 3 Sheets-Sheet 1 Filed July 24; 1944 INVENTOR. I firmaza K 4/Vf'$ ATTORNEY H. v. JAMES TIRE RETREADING DEVICE De c. 14, 1948.

3 sheets-sheet 2 INVENTOR. #29040 dime-.5

lrmm'r Filed July 24, 1944 Dec.14,1948.- H v, JA ES 2,456,063

' TIRE RETRBADING DEVICE Filed July 24, 1944 3 sheets-sneak 3 BY ii u ,vrramzx Patented 15cc. 14, 1948 UNITED STATES PATENT OFFICE TIRE RETREADING DEVICE Harold V. J ames,: Denver, Colo. Application July 24, 1944, Serial No. 546,266

7 3 Claims. (Cl. 18-18) 1 invention relatesto a tire retreading device and has for its principal object the provision of a highly eflicient vertical mechanism which will occupy aminimum of floor space and whichwill applya uniform mechanical pressure to the tread of -,the tire, thus eliminating the necessity for all air and steam bags.

.The invention is designed more particularly as an improvementover the structure illustrated and described inapplicants prio'r Patent No. 2,228,316 issued Ja'n. 4,1941.

Other objects means for supporting the mechanical pressure device so that it may be easily handled by one ,man regardless of its weight; to provide a supporting structure for the heating elements which will eliminate all hot spots and obtain a uniform temperature thi'rOi' hout theentire mold area; to provide means for assisting the operator in opening the, mold and for cushioning and supporting the latter when in the openposition; and to pro vide means for mounting the mold matrix rings in the ,mold housing which will eliminate machine operations on the latter and which will be adaptable'to receive a Wide varietyof different sized mold matrix rings.

Other objects and advantages reside in the de-' ta'il construction of the invention, which is designed for simplicity, economy, and efliciency.

These'will become more apparent from the following desc ription.

a In thefollowing detailed description of the in vention, reference is had ,to the accompanying drawing which forms a part hereof. Like nume'fr als'ref'er to like parts in all views of the. drawing and throughout the description;

Inthe' drawing:

QFig'. 1 is aside Fig. 4' is a vertical cross-section through the improved retreading device taken on the line Fig. 5 is airagm'entary perspective view of the interior of the mold housing.

Fig." 6 is detail perspective view illustrating the method of mounting a mechanical pressure shoe on it'sactuating' arms, as used. in thisdevicea detail sectional view'through' the of the invention are: toprovide' I view ofthe improved tire re-s treading device, illustrating the latter in the fixed bracket bearing for the jack screw employed in the improved tir retreading device.

Fig. 8 is a vertical, enlarged, fragmentary section through the mold housing taken on the line 8-8, Fig. 4.

Fig. 9 is a detail cross section through a heating bar employed in the device illustrating the method of securing a heating element therein.

In Fig. 4 only the top and bottom pairs of radial pressure shoe arms have been'illustrated. The remainder have been omitted to clarify the illustration.

.Theimproved retreading device is designed to support a tire casing in a vertical position and to apply mechanical expanding pressure to the interior of the tire casing to force it outwardly against an external, heated mold face.

The device comprises a circular, hollow housing formed in three sections, a .base section I 0 and two hinged sectionsll. The base section III is supported on suitable supporting legs I3, which are braced bymeans of suitable leg braces I2.

The hinged sections II are mounted on the extremities of the base section In upon suitable hinge pins l4 and may be clamped'together at.

section into which it is clamped by means of a. clamping nut I'I. By tightening the'clamping nut ll, the two sections may be rigidly clamped together. 7

When the clamp bar is released, the two sections II may be swung away from each other about the axis of the hinge pins I4, as shown in broken line in'Fig. 1. The amount of outward,

movement of these sections is limited by means of stop bars l8 which are secured at one of their extremities to the section I0 and; are provided with slotted openings I9 for receiving pins 20 fixed tothe hinged sections II. When the pins 20 reach the extremities of the openings l9, outward movement of. the sections II is stopped.

Each of the sections I I is provided with a cushioning bracket 2| from each of which a pull bolt 22 is suspended. The pull bolts pass through fixed brackets 23 on the section -IIJ. The pull bolts 22 are constantly pulled downwardly by means of helical compression springs 24. The springs act to cushion the closing action of the two hinged housing sections I l and to prevent them from falling together with damaging force. A resilient cushion member 25 surrounds each pull bolt. Thus it can be seen that as the sections H move inwardly, a portion of their weight will be absorbed by the bolts 22 to allow them to come gently together. When the sections move outwardly, they come to rest on the cushion members 25. The springs 24 also assist the operator in opening the section I I.

A pry boss 26 projects from each of the sections H adjacent? to the top thereofto allow'a pry bar to be. inserted therebetweerr to pry. the. two sections apart after the retreading operation has been completed.

Each section of the housing is providedwith an arcuate heating bar 28 which is" resiliently mounted between guide lugs 29 on its. inner. surface. The heating bars 28 are formed of a metal having a high thermal conductivity; such asaluminum, and each carries an imbedded electrical element 30, such we Calrod, from which it derives. its, heat. The Calrod, is, inset. in a. groovefintheinner iaceoi the heatingbar so. as. to be exposed to. theinner surface, thereof. The rods are, locked. in the. grooves. by indenting. the. edges ofth'e latter as shown at 58. The current. to the, heating elements is, conveyed. across the hinge points; of. the, adjacent sections through. suitable flexible. conduits 3].

.The actual, moldingofj the tire tread, is accomplished by means of a sectional matrix ring 32. The ring 32 isformedinthree sections I and I]; of the housing. The back of each matrixv rin sectionrests on the lugs 29in the housing sections fitting the sections and is lockedin place, therein by means of set screws. 33 accessible from. the exterior of the housing. The inner face of each matrix ring sectionprovides the mold" for the desired tire tread design. The. ring sections are quicklya'nd easily removable, by simply loosening,

the set screws 33 so that mold sections of'any. d'esired size. or design can be quickly and easily placed in the device.

The heating bars 28 are resiliently mounted between the guide lugs 29 upon suitable springs 10" and are each held in place'against' the. action ofthje springs by means of a pair of retaining bolts "H extending through the sections. Ill and H;.

Thebolt's' H of each pair are arranged in parallel relation so as, to allow free radial movement of thef'ba'rs 28without' binding. The bolts H are so adjusted asto allow the barsto normal'lyproject inwardly beyond the tops of; thelugs 29; as shown in Fig. Thus'whenthematrix ringsare resting" onthetopsof'the lugs 29theheating bars will be forced into contact therewithunder the influence of'the'springs The contacting arcuate' surfacesor the heating bars 2-8'and the matrix rings 32 are accuratelymachined to-holdthem. in uni"- rprin; contact overtheirentireareas so that a uniform transference of-heat is obtain'edto the matrix rings 3 2 'throughoutthe entire circumference of themold'. All contractionand expansion under the influence ofheat is accommodated by, the-springs- TU without affecting the contract bee tween the bars 28- and the matrix rings. The housing sections" l0- and H, are entirely open, through ventilating openings 55; and they donot contact the matrixrings so that' free circulation. oi! air is: allowed throughout the en-tirehousing; so that uniform heating of the matrix' results without undue heating of the housing.-

' Sincetheonly contact between" the matrix" rings 32 and the housing isat the tops' or the lugs'2'9, it is not necessary to machinethe entire; inner circumference of the housing. Only the: tops of the lugs needto be machined. This re- 4 duces manufacturing cost and reduces heat loss to the housing.

The entire tire casing is uniformly forced outwardly against the matrix rings by means of a mechanical pressure device. The latter consists of a jack screw 35 which is detachably supported at its inner extremity in a fixed bracket 36 and at its outer extremity by a hinged bracket 31. A bracket. frame: 43 is secured to the: side. of the lower. housing section lllli. The bracket; 31 is hingedly mounted on this frame on suitable hinge bolts 44. At the bracket 31 the jack screw is j ournalled in a bearing sleeve 38 and terminates in a hand wheel 39. The sleeve 38 is mounted adiacentitsinner extremity on a pivot pin 40 in the bracket 31. An ear 4| is formed on the sleeve 38 adjacent its outer extremity for receiving the upper. extremity of a connecting rod 42. The lower extremity of the connecting rod 42 is hingedly mounted on a hinge, pin 64 on the bracket frame 43"at a point outwardly from andiabovwthe axis of. the hinge. bolt 44;

The. above construction operates" as; follows? As the hand Wheel 39 is pulled outwardly, the:

bracket" 31. will, swin outwardly. This normallywould' swing the inner extremity of the; jack" screw. 35 upwardly which would? not'b'e; possible since it would. strike the, tire casing; in the mold. This isprevent'ed', therefore, by'the actijonofthe: connecting rod 42' which tends to: cause the inner" extremity of the jack screw to follow asubst'antially. level; pathuntil it leaves the mold and then. swings. it. outwardly to. the broken. line position, of. Fig. 4, whereitwill be outv of the way-ferrerriovingand replacing the tire, casings.

Qutwardjmovement of'the bracket 31fisillmited bymeans. of projecting feet 45' formed? on. the. hinged bracket31; These. feet contact abutment's. 46' on. the. frame 43. when the bracket. 3Treaches... its. extreme outward position to support the me:- chanical pressure. mechanism in the. outL-off-use. positiom When the,hihgedibracketi31'is swung. upwardly... the connecting rod also acts on the sleeve 381t0. accurately align the jack screw 35, with, its bear ing, position in the inner bracket" 352 The screw terminates; in a, spool. 21" which: slips; into the bracket 36 and'i's locked therein. by meansoff a. set screw 41. The spoolis rotatably mounted; on the jack screw so that the setscrew prevents axial withdrawal, of the jack. screw but allows free rotation thereof;

The jack. screw 35. supports a mechanical; ex.-- panding. device which is described more iirdetaili in applicant's prior Patent 1%.. 2.2283 61. Briefly, this device comprises two nutsfilithreaded' onto opposite extremities of the jack screw. 35. The threads. on the latter are. of'opnosite. at the opposite extremities. so that; rotation. of. the jack screw in. one direction, will. separate the, nuts 48' and rotation in the other directionwflli cause them. to.- approach each other...

A circular seriesotpressure. shoes-.52.surmund;. the jack screw between, the nuts. 48. Each shoe is hingedlysecuredt'o a fitting 5| hymeamlofja hinge. pin. 6.0. The. extremitiesof. a.pair. oh radial toggle arms 49? are. hinged'in. the. fitting onlhi'ngaz pins 62: A 'tooth'ed'clip 63 is secured to each-arm; 49. The clips are provided. with intermeshins gear teeth 5D. The opposite extremity, of. one:v toggle arm. of. each pairv is connected. to oneof the nuts 4'8 and the. other arm. is. similarly cone-- nect'edtothe other. nut, 48. 'Iilius, ,when.thenuts. approach each other,,the. fittiiigsa 51. areaforqed outwardlvthusexpanding the entire series of shoes. When the nuts are separated from each other, the shoes are drawn inwardly toward the jack screw in overlapping relation.

The shoes are curved to approximate the arc of their expanded circumference and each shoe is provided on its outer surface with a central ridge 53 which extends into a medial groove formed in the inner face of a resilient peripheral cushion band 54. The band 64 is formed from resilient compressible and extensible material, such as rubber, and forms the contact member for the interior of the tire casing being retreaded.

Thus it can be seen that when the hand wheel 39 is rotated in one direction, the band 54 will be expanded radially outward to force the tire casing into the matrix rings 32; and when rotated in the other direction, will be contracted away therefrom. The contraction can be extended until the shoes 52 lie close to the jack screw 35, as shown in the broken line in Fig. 4, at which time the band 54 can be entirely removed from the shoes.

It will be noted that one extremity of each of the shoes 52 is inset as shown at 69 to allow them to form a perfect circular alignment in their working diameter.

A dowel pin 6| is positioned in one of the sections H so as to enter a dowel hole in the other section to accurately align the two sections when they are clamped together in the closed position. The extremities of the clamp screws 33 are pointed so as to enter countersunk depressions in the matrix rings to accurately locate and lockthem in position.

When the device is used for tire casings of smaller diameter, the matrix rings, of course, are of a smaller internal diameter than those illustrated, the difference in size being taken up by increasing the thickness of a contact pad 34 which may be formed on the back of the ring sections. To save metals and weight this pad may be formed hollow as illustrated, if desired.

It is desired to call attention to the bearing construction in the fixed bracket 36 as illustrated in detail in Fig. 7. The stem of the set screw 41 is hollow at the point to receive a detent spring 65. The spring acts against a pointed detent head 66 which forms the extremity of the screw shank. A plunger 61 extends from the 1 head 66 axially outward to project from the screw 41. The point of the detent head enters a peripheral receiving groove in the spool 2'! on the extremity of the jack shaft, and when the screw 41 is tightened against the head 66 the latter is locked in place in the groove.

If the screw 41 is loosened, however, the head is retained in the groove only by the action of the spring 65, which acts to temporarily hold the jack shaft in place. This construction enables a single operator at the front of the device to withdraw and reinsert the extremity of the jack screw without danger of its falling from place until the screw 41 is tightened.

The hinged sections I l and the base section II] are reinforced by means of suitable reinforcing ribs 56 and 51 to prevent distortion from the extreme pressures and temperatures placed thereon.

While a specific form of the improvement has been described and illustrated herein, it is desired to be understood that the same may be varied, within the scope of the appended claims, with- Having thus described the invention, what'is claimed and desired secured by Letters Patent is:

out departing from the spirit of the invention.

1. A tire retreading device comprising an arcuate, trough-like base section; a similar arcuate trough-like side section hinged to each extremity of the base section, the three sections cooperating when closed to form a complete, annular internal channel; an arcuate heating bar mounted within the trough of each section so as to be radially movable therein; an electric heating element associated with said heating bar to heat the latter; an arcuate tire tread matrix member positioned in each section adjacent said heating bar; springs urging said heating bar against the matrix members; and a pair of retaining bolts extending through each of said trough-like sections from the heating bar therein, the bolts of each pair being parallel to each other and extending completely through said sections to the exterior thereof, said bolts being slidable in the sections and being provided with means on their outer extremities to limit their inward movement.

2. A tire retreading device comprising an arcuate, trough-like base section; a similar arcuate trough-like side section hinged to each extremity of the base section, the three sections cooperating when closed to form a complete, annular internal channel; an arcuate heating bar mounted within the trough of each section so as to be radially movable therein; an electric heating element associated with said heating bar to heat the latter; an arcuate tire tread matrix member positioned in each section adjacent said heating bar; springs urging said heating bar against the matrix members; a pair of retaining bolts extending through each of said trough-like sections from the heating bar therein, the bolts of each pair being parallel to each other and ex" tending completely through said sections to the exterior thereof, said bolts being slidable in the sections and being provided with means on their outer extremities to limit their inward movement; and helical compression springs surrounding said bolts between said heating bars and said sections and acting to urge the former against said matrixes.

3. A pneumatic tire retreading device comprising: an annular hollow housing open at its axial face; an annular heating bar within said housing; means for preventing lateral movement of said bar yet allowing radial movement thereof; an annular matrix ring supported within said housing and within said heating bar; spring means urging said heating bar radially against said matrix ring; and means for guiding the spring-urged movement of said heating bar in a radial direction.

HAROLD V. JAMES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,745,145 Brown Jan. 28, 1930 1,879,194 Grange Sept. 27, 1932 1,996,971 Murphy Apr. 9, 1935 2,088,130 Broering et al July 27, 1937 2,219,800 Allen Oct. 29, 1940 2,228,316 James Jan. 14, 1941 2,267,243 MacMillan Dec. 23, 1941 2,338,462 Seaton Jan. 4, 1944 2,345,172 Bacon Mar. 28, 1944 2,370,972 Kraft Mar. 6, 1945 

